1. Field of the Invention
This invention relates, generally, to syringes, and particularly, syringes designed for shielding the needle of the syringe so as to prevent accidental sticks.
2. Prior Art
In the medical field, prevention of accidental sticks by used needles is a constant concern. Countless injections using syringes are made every day in a variety of settings. As with all medical procedures, prevention of infection is a primary concern. Syringes are typically packaged with a protective cover over the needle. The operator removes this cover prior to administering the injection.
If the syringe has not come pre-filled, the operator will draw up the medication, which is in fluid form, into the syringe. The fluid is drawn into the syringe by inserting the needle into the container of medication fluid. The syringe plunger is pulled away from the needle end of the syringe barrel, creating a vacuum in the syringe. The vacuum causes the medication to be drawn into the syringe through the needle. The operator observes the position of the syringe plunger in relation to volume marks found on the syringe body. When the plunger has reached the desired mark corresponding to the correct dosage, the operator removes the needle from the container and holds the syringe, needle end up, so that all air in the syringe will go to the needle. The operator then pushes in the plunger slightly, sometimes tapping the side of the syringe, until any air in the syringe has been purged out through the needle.
The operator sets the syringe aside and prepares the injection site. Once the injection site is prepared, the operator inserts the needle into the patient and pushes in the plunger, injecting the medication into the patient. When the plunger has been fully depressed into the syringe body, the operator removes the needle from the patient.
The next few moments are crucial in infection control. The used syringe, immediately after it has been removed from the patient, is commonly known as a dirty needle. Frequently, hospitals and physicians' offices have special receptacles in the patient and examining rooms for disposal of dirty needles. The operator will usually replace the cover on the needle and place the syringe into a proper receptacle. But in the few moments, or even the few seconds, between the removal of the syringe from the patient and the placement of the cover over the needle an accidental dirty needle stick can occur.
Dirty needle sticks can occur during this time for any number of reasons. In emergency rooms and other settings, patient may be fighting the treatment, and may push the used needle into the operator or other medical professionals around the patient. Children or even some adults become frightened by the pain of a shot and may react, involuntarily or voluntarily, by jerking or some other motion which can cause an accidental stick. Other factors not attributable to the patient include fatigue of the operator, poor lighting conditions (e.g. at night in a patient's dark room), and simple lapses in following procedures. Some of these conditions may cause the operator to stick themselves when simply replacing the cover on the needle.
Numerous attempts have been made to provide a device which will prevent or minimize dirty needle sticks. U.S. Pat. No. 4,973,316 to Dysarz discloses a syringe in which a compressed spring assembly within the syringe barrel is used in combination with a trigger assembly. The device in Dysarz retracts the needle after the injection is given. However, the device in Dysarz requires the use of numerous moving parts and an internal spring in the syringe body. The device in Dysarz also requires separate manipulation of the syringe by the operator after giving the injection. Dysarz does not disclose automatic shielding of the needle with the administration of the injection.
What is needed is a syringe which will automatically cover the needle upon the administering of the injection. An ideal syringe would cover the needle without the operator having to use a second hand and would cover the needle simultaneously with the giving of the injection. The automatic covering feature should not interfere with the syringe's ability to perform all the functions of a conventional syringe, to include the ability to draw up medications and purge air from the medication.